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Ambulatory Impedance pH Monitoring Gastroenterology of the



                                                                                              Classifying GERD
                                                                                              Combined impedance-pH monitoring

                               Ambulatory                                                     represents a change in the GERD testing
                                                                                              paradigm. The currently accepted gold
                                                                                              standard for assessing GERD is the 24-hour

                             Impedance-pH                                                     pH monitoring study, which detects the

                                                                                              reflux of acidic material into the esophagus.
                                                                                              This conventional study employs a pH sensor

                                                                                              placed 5 cm above the lower esophageal
                                                                                              sphincter to detect when pH drops from
                                                                                              above 4.0 to below 4.0, thereby indicating
                                                                                              acid reflux. Although 24-hour pH monitor-

                         A NEW TOOL FOR DIAGNOSING                                            ing identifies when pH drops below 4.0, it
                                                                                              provides limited information about pH that
                                     NON-ACID GERD                                            rises above 4.0 (i.e., non-acid reflux).

               By Joel R. Montbriand,
                     MD, FACP, FACG,
            and Andrew D. Spears, MD
             Gastroenterology of the Rockies

Gastroesophageal reflux disease (GERD)         Interestingly, new research indicates that
is the most common GI-related diagnosis       GERD should not be ruled out for patients
made during physician office visits.           who fail acid-suppressive medical therapy.
According to the American Academy of          Unresponsive symptoms may be caused by
Family Physicians, GERD affects approxi-      non-acid GERD. In other words, medical

mately 19 million Americans. Additionally,    therapy may suppress stomach acid yet
its treatment costs about $10 billion a       not remove the reflux itself, which is why
year, making GERD the most expensive
                                              symptoms may continue. In fact, research
disease of the alimentary tract.
                                              has validated that patients with persistent
                                              symptoms while on acid-suppressive              The catheter contains multiple impedance
GERD is often diagnosed through a well-       medical therapy have non-acid GERD              sensors and a pH sensor.
taken patient history. For patients who       about 35 percent of the time. 7

present with classic GERD symptoms,                                                           Using impedance-pH monitoring, gastro-
such as heartburn or regurgitation, the       Until recently, it was impossible or difficult   enterologists can characterize both acid
primary care practitioner typically recom-    to accurately detect non-acid GERD. How-        and non-acid reflux events. The test even
mends lifestyle changes and administers an    ever, physicians at Gastroenterology of the     provides detailed characterization of the
empirical trial of acid-suppressive medical   Rockies are now able to accurately detect       reflux episode’s composition (gas, liquid
therapy. Patients who respond to therapy
                                              non-acid GERD using a new diagnostic tool       or mixed). Patients who are medicated or
are diagnosed with GERD. Those                called combined impedance-pH monitor-           unmedicated may undergo the test.
who fail to respond to therapy—               ing. In fact, by combining measurement of       Like the traditional 24-hour pH test, the
somewhere between 35 and 40 percent           impedance and pH, it is possible for our        impedance-pH catheter is passed through
of medicated patients —are referred to a
                                              physicians to not only identify GERD but        the nose and into the esophagus. The cath-
gastroenterologist for further evaluation.    also determine whether acid or non-acid         eter remains in place for 24 hours. During
                                              GERD is the likely cause of symptoms.           this time, the amount of acid and non-acid

reflux entering the esophagus from the                          downloaded and analyzed using dedicated                  One study, conducted by Dr.
stomach is continuously measured. An                           software. The software quantifies the                     I. Mainie and associates from

                                                                                                                                                                Physician-Focused News from Boulder Community Hospital
acid event is defined as a drop of pH from                      number of GERD episodes, bolus presence                  the Medical University of South
above 4.0 to below 4.0. Non-acid reflux is                      time at various levels in the esophagus,                 Carolina in Charleston, evaluated
an impedance-detected event during which                       and esophageal acid exposure time.                       monitoring esophageal imped-
the pH stays above 4.0 and does not drop                                                                                ance as well as acidity on 121
more than 1 pH unit.                                           Based on the measurements, patients                      medicated patients with typical
                                                               fall into one of three symptom                           GERD symptoms. The researchers
To measure impedance, the catheter’s                           association groups:                                      reported that 42 percent of the
impedance sensors are positioned through-                                                                               patients had non-acid reflux; 10
out the esophagus. Impedance sensors                           • Acid reflux associated with symptoms
                                                                                                                        percent had acid reflux; and the
detect reflux as bolus movement along the                                                                                remaining 48 percent had neither
                                                               • Non-acid reflux associated
entire length of the esophagus and even up                                                                              acid nor non-acid reflux. Even
                                                                 with symptoms
into the mouth and, potentially, the airway.                                                                            when monitoring 52 patients with
Based on different impedance patterns, a                       • No association of reflux and symptoms                   atypical symptoms, such as cough,
reflux episode can be classified as contain-                                                                              19 percent had non-acid reflux and
ing gas, liquid or both. Air conducts elec-                    A study indicating non-acid reflux is useful              4 percent had acid reflux index.9
tricity poorly and therefore has very high                     in selecting patients who may benefit from
impedance, whereas liquid gastric contents                     anti-reflux surgery, perhaps the best way to              Agrawal and colleagues10 also used
have low impedance.                                            treat the condition.5                                    combined impedance-pH monitoring
                                                                                                                        of symptoms in 75 patients. Overall,
During the monitoring period, patients                         Acid and                                                 63 percent of patients had com-
are instructed to reproduce their daily                                                                                 pletely negative studies (no reflux
routine as much as possible. Impedance
                                                               Non-acid Reflux
                                                                                                                        association with any symptom); 34
and pH events are recorded with a sample                       Impedance-pH monitoring has been shown                   percent had symptoms that were
frequency of 50 Hz and stored on a data                        to record reflux accurately at all pH levels              positive for non-acid reflux; and 3
logger. Upon completion of the study,                          and is emerging as a useful tool to study                percent were positive for acid reflux.
the catheter is removed, and the data is                       both acid and non-acid GERD.6,8
                                                                                                                        “GERD” Continued on page 7

                         172 Patients with Persistent Symptoms on Medication
                                                                                                                        Symptom Index
                               Impedance-pH Monitoring on Medication
                                                                                                                        Typical GERD symptoms
                                                                                                                        • Regurgitation
        Patients with Typical Symptoms                               Patients with Atypical Symptoms                    • Heartburn
                     N=99                                                          N=73
                                                                                                                        Atypical GERD symptoms
                                                                                                                        • Cough
                                                                                                Association             • Throat clearing
            No Reflux                  Non-acid
           Association               Association                             No Reflux              19%                  • Non-cardiac chest pain
              41%                       48%                                 Association                                 • Asthma
                                                                               78%                                      • Chronic cough
                                                                                                          Acid          • Laryngitis
                          Acid                                                                                          • Chest pain
                          11%                                                                                           Non-acid reflux symptoms tend
                                                                                                                        to be higher in the esophagus:
                                                                                                                        • Regurgitation
                                                                                                                        • Cough
   Inder Mainie, R. Tutuian & D. O. Castell; Medical College of SC; Symptoms on PPI Therapy Associated with Non-acid,
   Acid or No Reflux; ACG Presentation; October 2004

enhances analysis of CT colonography,
complex body imaging cases and spine
                                                  Continued from page 5

                                                                                                                                                              Physician-Focused News from Boulder Community Hospital
and orthopedic cases.
                                                  Similar results were found by Katz and           Joel Montbriand, MD, and
While the PACS for the interpreting
radiologists has been in place only a short
                                                  colleagues. In this study of 71 patients         Andrew Spears, MD, are
                                                  exhibiting symptoms while on therapy, 30         board-certified
time, I have observed more efficient inter-        percent had non-acid reflux associated with
pretation and service to the ordering care        symptoms and 11 percent had acid reflux.     11   gastroenterologists with
provider. Radiologists are no longer                                                               Gastroenterology of the
limited to reading what is available at           Thus, impedance-pH monitoring in medi-           Rockies. They can be
their sites. We are reading cases system-         cated patients with either typical or atypical
wide, across facilities. Radiologists now
                                                                                                   reached at 303-444-4066.
                                                  symptoms has been shown to be a useful
have the capacity to discuss cases over           way to exclude GERD—acid or non-acid—
the phone with either radiology colleagues
                                                  as the cause.                                    1 Shaheen N, Hansen R, et al. The Burden
or with the ordering care providers, while                                                         of Gastrointestinal and Liver Diseases, Am J
looking at the case on their separate             Conclusion                                       Gastroenterol 2006;101:2128–2138.
remote workstations/monitors. I have                                                               2 Tutuian R, Castell D. Gastroesophageal reflux
                                                                                                   monitoring: pH and impedance, GI Motility online;
found this to be a wonderful new tool             Non-acid reflux is an important cause of          May 16, 2006.
to improve patient care and increase              persistent symptoms in patients who fail         3 Katz P. Evaluation of Patients With Symptoms
efficiency for care givers.                        to respond to acid-suppression medical           of Gastroesophageal Reflux—Role of Reflux
                                                                                                   Monitoring, American College of Gastroenterology
                                                  therapy. Combined impedance-pH moni-             70th Annual Scientific Meeting and Postgraduate
Now that the PACS web product is fully            toring is an effective method of testing         Course; October 28, 2005–November 2, 2005,
operational, I believe all care providers         patients with persistent symptoms on or          Honolulu, Hawaii.
within the network will take advantage and        off acid suppressive therapy, for it can         4 Castell D, Kahrilas PJ, Richter JE, et al.
                                                                                                   Esomeprazole (40 mg) compared with lansoprazole
utilize the system. In the near future, we will   clarify whether symptoms are associated          (30 mg) in the treatment of erosive esophagitis. Am J
also adopt Voice Recognition (VR) technol-        with acid or non-acid reflux.                     Gastroenterol 2002;97:575–583.
ogy, which will allow for greater efficiency                                                        5 Tutuian R, Mainie I, et al. Non-acid Reflux in
                                                  Although this new type of monitoring             Patients with Chronic Cough on Acid-Suppressive
and accuracy as we interpret our studies.                                                          Therapy, Chest, Aug 2006;130:386–391.
                                                  represents a shift in the reflux-testing          6 Castell D, Mainie I, Tutuian R. Non-acid
Dr. Helgans is a board-certified                   paradigm, it still presents traditional pH       Gastroesophageal Reflux: Documenting its
radiologist who practices general                 information. Data from the pH sensor             Relationship to Symptoms Using Multichannel
                                                                                                   Intraluminal Impedance (MII), Trans Am Clin Climatol
diagnostic imaging at Boulder                     reports esophageal acid exposure time.           Assoc. 2005;116:321–334.
                                                  Impedance data simply expands the                7 Mainie I, Tutuian R, et al. Acid and non-acid reflux
Community Hospital. He can be                     amount of acquired information to identify       in patients with persistent symptoms despite acid
reached at 303-440-2170.                          any relationship between symptoms and
                                                                                                   suppressive therapy: A multicentre study using
                                                                                                   combined ambulatory impedance-pH monitoring, Gut
                                                  either acid or non-acid reflux events.            2006;55:1398–1402.
                                                  Armed with this comprehensive diagnostic         8 Vela MF, Camacho-Lobato L, Srinivasan R, Tutuian
  If you are a clinician who would like                                                            R, Katz P, Castell D. Intraesophageal impedance and
                                                  information, the gastroenterologist can          pH measurement of acid and non-acid reflux: effect of
  access to the Boulder Community
                                                  make a fully informed diagnosis.                 omeprazole. Gastroenterology. 2001;120:1599–1606.
  Hospital PACS, please contact us                                                                 9 Inder Mainie I, Tutuian R, Castell D. Symptoms on PPI
  for an informational packet and                 Gastroenterology of the Rockies                  Therapy Associated with Non-acid, Acid or No Reflux,
  enrollment form:                                physicians currently offer patients com-
                                                                                                   ACG Presentation, October 2004.
                                                                                                   10 Agrawal A, Hila A, Blonski W, et al. Symptoms of
                                                  bined impedance-pH monitoring studies            both acid and non-acid reflux occur almost exclusively
  Joe Mikoni, BCH Imaging
                                                  at the practice’s Lafayette office. Sandy         in the upright position. Gastroenterology. 2006;130:
  Department Director,                                                                             A-163.
                                                  Brubaker, a nationally recognized GERD
  303-440-2204, or Dan Spencer, BCH                                                                11 Katz P, Gideon M, Tutuian R. Reflux Symptoms on
                                                  health care practitioner and trainer,            Twice-Daily (BID) Proton Pump Inhibitor (PPI) Associated
  PACS Administrator, 303-440-2242,
                                                  assists with these studies.                      with Non-Acid Reflux; a Manifestation of Hypersensitive
  or email                                                                        Oesophagus. The Association of GI Physiologists Annual
                                                                                                   General Meeting; December 5, 2005.


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